Genetic redundancy aids competition among bacteria in symbiosis with squid
(PHYSorg.com Biology)

The molecular mechanism used by many bacteria to kill neighboring cells has redundancy built into its genetic makeup, which could allow for the mechanism to be expressed in different environments. Some strains of luminescent bacteria that compete to colonize the light organs of the Hawaiian bobtail squid kill nearby cells of different bacterial strains using the `type VI secretion system (T6SS).` Researchers at Penn State and the University of Wisconsin-Madison have now shown that the genomes of these bacteria contain two copies of a gene required for T6SS and that the system still works when either copy of the gene is disabled, but not both.